Method and apparatus for detecting leaks

ABSTRACT

The present invention relates to a sensor apparatus configured to detect the presence of a gas, such as a tracer gas and a leak detection apparatus configured to detect the presence of a tracer gas and indicate the location of a leak. The leak detection apparatus may further be configured to quantify the leak rate at the leak location.

BACKGROUND AND SUMMARY OF THE INVENTION

[0001] The present invention relates to methods and apparatus to detectthe presence of a gas and in particular to methods and apparatus for thedetection of the presence of a tracer gas in a leak testing environment.

[0002] In traditional leak testing apparatus either an interior regionor an exterior region of a part under test is placed at a higherpressure than the other of the interior region or exterior region of thepart under test. As such, if a leak is present in the part under test,the gas will flow from the higher-pressure side of the part under testto the lower pressure side of the part under test. One method to monitorthis flow of gas and hence detect the presence of a leak is with apressure decay apparatus which monitors the pressure of thehigher-pressure side of the part under test. A decrease in pressurecould be an indication of a leak. Another method uses a massspectrometry based apparatus to test for the presence of a tracer gas onthe lower pressure side of the part under test. The tracer gas havingbeen introduced on the higher-pressure side of the part under test.

[0003] Such apparatus provide the operator of the apparatus with anindication of whether a part under test has a leak or at least whetherthe part under test has a leak that exceeds a predetermined thresholdvalue. Typically, the customer specifies the threshold value and theoperator sets the threshold value of the apparatus. If the operator ofthe leak testing apparatus receives an indication from the leak testingapparatus that the part under test contains an unacceptable leak, i.e.the leak exceeds the threshold value, the operator knows that the partunder test is rejected and the operator places the part in a queue forfurther testing. However, the operator has no knowledge of the locationof the leak or whether subsequently rejected parts are leaking fromapproximately the same location or a different location.

[0004] In order to determine the location of the leak further testing istraditionally required. Once the location of the leak is determinedchanges can be implemented to the manufacturing process to minimize thenumber of future rejected parts. The location of the leak is typicallydetermined in one of two methods. First, for larger leaks the locationof the leak is determined by pressurizing the rejected part andsubmerging the rejected part into a water bath. The location of the leakis determined based on the presence of air bubbles emanating from theleak site. Second, for smaller leaks the location of the leak can bedetermined by pressurizing the rejected part with a tracer gas andpassing a tracer gas detector, such as a sniffer apparatus, over thepotential leak areas of the rejected part. The tracer gas detector drawsthe gas proximate to a probe on the tracer gas detector apparatus, intothe probe, and past a detector to detect the presence of tracer gas. Onemethod of drawing the gas proximate to the probe is with a fan unit thatdraws gas into the probe and eventually past the detector. The leak siteis then noted and potentially changes to the manufacturing process willbe implemented.

[0005] The two stage process described above requires additionalresources, delays the determination of the location of the leak for agiven part under test and delays the determination of whether thelocation of the leak is repeatable from rejected part to rejected part.Further, the above two stage process is very operator dependent, in thatthe operator must visually recognize the leak, denote the leak location,and subject each rejected part to a consistent testing procedure.Additionally, results vary from operator to operator in the ability ofeach operator to recognize leaks and denote leak locations.

[0006] In addition, traditional apparatus often use mass spectrometryequipment to detect the presence of a leak due to the need to detectsmall quantities of the tracer gas. Such apparatus require that the gaslocated on the lower pressure side of the part under test be drawn to asensing element to analyze the gas to detect the presence of the tracergas.

[0007] As such, a need exists for a leak detection apparatus thatprovides an indication of the location of a leak in a part under testgenerally concurrently with the initial leak testing of the part.Additionally, a need exists for a leak detection apparatus that providesan indication of the location of a leak and an indication or measurementof the leak rate. Further, a need exists for a cost effective leakdetection apparatus.

[0008] In one exemplary embodiment, the present invention includes aleak testing apparatus configured to detect the presence of a leak in apart under test. The leak testing apparatus of the present invention inone example is further configured to determine the location of the leakin the part under test. In another example the leak testing apparatus isfurther configured to determine both the location of the leak in thepart under test and the leak rate of the corresponding leak.

[0009] In another exemplary embodiment, an apparatus for detecting thepresence of at least one leak in a first region of a part under test andfor localizing the location of the at least one leak, wherein a firstside of the first region contains a tracer gas and is at a higherpressure than a second side of the first region such that the tracer gaswill emanate through the at least one leak from the first side to thesecond side comprises a plurality of sensors positioned proximate to thefirst region, each sensor being configured to detect the presence of atracer gas emanating from a leak and to provide a sensing signal; and acontroller connected to the plurality of sensors. The controllerconfigured to provide a leak detection signal in response to at least afirst sensor of the plurality of sensors detecting the presence of thetracer gas, the leak detection signal including leak detectioninformation representative of the location of the leak in the firstregion based on the sensing signals received from at least the firstsensor and a second sensor of the plurality of sensors. In one example,the apparatus further comprises an indicator configured to provide avisual indication of the location of the leak. In one variation, theindicator includes a display configured to display a firstrepresentation of the part under test and a sensor icon positioned onthe first representation, the sensor icon corresponding to a location ofa first sensor which is proximate to the location of the leak. Inanother variation, the indicator includes a display configured todisplay a first representation of the part under test and a leak graphicpositioned on the first representation, the position of the leak graphiccorresponding to a location of a first sensor which is proximate to thelocation of the leak.

[0010] In one exemplary method, a method of monitoring a part under testto determine whether a first region contains a leak, the methodcomprises the steps of locating a plurality of sensors proximate to thefirst region, each of the plurality of sensors configured to detect thepresence of a tracer gas emanating from the leak and to provide asensing signal; monitoring each of the plurality of sensors to determineif the tracer gas is being detected by any of the plurality of sensors;and providing a leak detection signal in response to at least a firstsensor of the plurality of sensors detecting the presence of the tracergas, the leak detection signal including leak location informationrepresentative of the location of the leak in the first region based onthe sensing signals received from at least the first sensor and a secondsensor of the plurality of sensors. In one example, the method furthercomprises the step of providing a first indication of the location ofthe leak. In one variation, the first indication includes displaying ona display a first representation of a part under test and a sensor iconpositioned on the first representation, the sensor icon corresponding toa location of a first sensor which is proximate to the location of theleak. In another variation, the first indication includes displaying ona display a first representation of a part under test and a leak graphicpositioned on the first representation, the position of the leak graphiccorresponding to a location of a first sensor which is proximate to thelocation of the leak.

[0011] In yet another exemplary embodiment a computer readable media foruse in a leak testing application to determine which of a plurality ofsensors is proximate to a leak in a part under test comprises a softwareportion configured to load a data file corresponding to the location ofthe plurality of sensors, to monitor the plurality of sensors todetermine if any of the plurality of sensors has detected the presenceof a leak, to determine the location of the leak if at least a firstsensor of the plurality of the sensors detected the presence of theleak, and to provide a visual indication of the location of the leak ifat least the first sensor of the plurality of the sensors detected thepresence of the leak. In one example, the software portion is furtherconfigured to provide a first representation of the part under test anda first sensor representation of the at least first sensor positioned onat least the first representation of the part under test. In anotherexample, the visual representation of the at least first sensor is asensor icon. In yet another example, the software portion is furtherconfigured to determine the location of the leak by determining whichsensor of the plurality of sensors detected the maximum concentration ofa tracer gas emanating from the part under test. In still a furtherexample, the software portion is further configured to determine thelocation of the leak by determining which sensor of the plurality ofsensors first detected the presence of a tracer gas emanating from thepart under test. In still yet a further example, the software portion isfurther configured to determine the leak rate of the leak in the partunder test. In one variation, the software portion further configured toprovide a leak graphic positioned on the first representation of thepart under test at a location proximate to the location of the leak.

[0012] In a further exemplary embodiment, the present invention includesa sensor apparatus configured to detect the presence of a gas, such ashelium or hydrogen. In one example the sensor apparatus includes asensor controller and is a networkable sensor apparatus, such that thesensor apparatus is capable of sharing information with other devicesacross a network. In another example, the sensor apparatus is configuredto detect the presence and concentration of a gas, such as helium orhydrogen. In yet another example, the sensor apparatus is configured tobe incorporated into a component to detect the presence of a gas.

[0013] In yet a further exemplary embodiment, a sensor apparatus fordetecting the presence of a leak in a part under test, the part undertest being pressurized with a gas including a tracer gas comprises ahousing; a sensor configured to detect the presence of the tracer gasand to generate a sensing signal; at least a first portion of the sensorbeing contained in the housing; and an I/O interface coupled to thehousing, the I/O interface being configured to provide a firstconnection corresponding to an analog output and a second connectioncorresponding to a network output; and a sensor controller connected tothe sensor and the I/O interface and configured to generate an outputsignal based on the sensing signal generated by the sensor, the sensorcontroller further configured to determine if a network is presentacross the second connection of the I/O interface and to generate a datapacket for transmission over the network if the network is present, thesensor controller being contained in the housing;. In one example, thesensor includes a thermal conductivity transducer. In one variation, aportion of the thermal conductivity transducer is accessible from anexterior of the housing and is positioned proximate to the exterior ofthe housing. In another example, the sensor controller is configured todetect the presence of a first network and the presence of at least oneadditional network. In one variation, the sensor controller isconfigured to provide the analog output over the first connection whenneither the first network nor the at least one additional network arepresent. In yet another example, the sensor apparatus is a stand-aloneleak detection apparatus, the sensor apparatus further comprising apower supply positioned within the housing and coupled to at least thesensor controller and an indicator viewable from the exterior of thehousing, the indicator being configured to provide an indication of thepresence of the tracer gas.

[0014] In still a further exemplary embodiment, a gas sensor apparatusfor detecting the presence of a gas comprises a housing including afirst outer surface; a sensor configured to detect the presence of thegas and to generate a sensing signal, the sensor including a transducerportion, the transducer portion positioned proximate to the first outersurface of the housing such that the transducer portion is contactableby the gas; a sensor controller connected to the sensor and configuredto generate an output signal based on the sensing signal generated bythe sensor; and wherein at least a portion of the sensor and the sensorcontroller are contained within the housing. In one example, the gassensor apparatus further comprises an I/O interface being coupled to thehousing and configured to connect the sensor controller to at least onedevice remote from the gas sensor apparatus. In one variation, theoutput signal of the sensor controller is a scaled analog output signalrepresentative of the amount of the gas detected by the sensor, thescaled analog output signal being made available to the at least oneremote device through a first connection of the I/O interface. Inanother variation, the output signal of the sensor controller is adigital signal representative of the amount of the gas detected by thesensor, the digital signal being made available to the at least oneremote device through a second connection of the I/O interface. In stillanother variation, the I/O interface further includes at least onetransceiver configured to receive the digital signal from the sensorcontroller and to generate and transmit a data packet containing thedigital signal. In another example, the gas sensor further comprises anindicator configured to provide a visible indication signal, the visibleindication signal being representative of the presence of the gas andthe visible indication signal being viewable from the exterior of thehousing.

[0015] In still another exemplary embodiment, a sensor apparatus for usewith a network comprises a housing; a sensor configured to detect thepresence of a tracer gas and to generate a sensing signal, the sensorincluding a first sensing portion, the first sensing portion beingpositioned such that the first sensing portion is contactable by thetracer gas; a sensor controller connected to the sensor and configuredto generate an output signal based on the sensing signal generated bythe sensor; a network controller connected to the sensor controller andconfigured to generate a network data packet, the network data packetincluding information based on the output signal generated by the sensorcontroller; a network interface connected to the network controller andadapted to connect the sensor apparatus to the network; wherein thehousing is configured to contain at least a first portion of the sensor,the sensor controller and the network controller. In one example, thesensor includes a thermal conductivity transducer. In still anotherexample, the sensor apparatus further comprises an indicator coupled tothe sensor controller, the indicator including a first indicatorconfigured to provide status information related to the sensor apparatusand a second indicator configured to provide an indication of thepresence of the tracer gas.

[0016] Additional features of the present invention will become apparentto those skilled in the art upon consideration of the following detaileddescription of the preferred embodiment exemplifying the best mode ofcarrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The detailed description of exemplary embodiments particularlyrefers to the accompanying figures in which:

[0018]FIG. 1 is a diagrammatic representation of a leak testingapparatus of the present invention configured to test for a leak in apart under test having a first potential leak region;

[0019]FIG. 2 is a diagrammatic representation of the leak testingapparatus of FIG. 1 configured to test for a leak in a part under testhaving at least a first and a second potential leak regions;

[0020]FIG. 3 is a perspective view of a sensor array comprising aplurality of sensors and a fixture whereto the plurality of sensors areaffixed, the plurality of sensors being positioned adjacent a part undertest having a first potential leak region, the part under test being atorque converter and the first potential leak region being a weld joint;

[0021]FIG. 4A is a bottom view of the sensor array and the fixture ofFIG. 3 showing a sensing element of each of the plurality of sensors;

[0022]FIG. 4B is a perspective view of the sensor array and the fixtureof FIG. 3;

[0023]FIG. 5 is a perspective view of the sensor array, the fixture, andpart under test of FIG. 3 showing the sensor array and the fixtureadjacent the part under test;

[0024]FIG. 6 is a cross section of FIG. 5 along lines 6-6 showing thepositioning of a first sensor and a second sensor in the sensor arrayrelative to the position of the first potential leak region;

[0025]FIG. 7 is a flow chart of a first exemplary embodiment of leaktesting software, the leak testing software having a set up portion anda operator portion;

[0026]FIG. 8 is a flow chart showing a first exemplary embodiment of theset up portion of the leak testing software of FIG. 7;

[0027]FIG. 9 is a flow chart showing a first exemplary embodiment of theoperator portion of the leak detection software of FIG. 7.

[0028]FIG. 10 is a flow chart of the first exemplary embodiment of atesting routine of the operator portion of the leak testing softwareillustrated in FIG. 9;

[0029]FIG. 11 is experimental sensor output of the leak testingapparatus of the present invention, the experimental data related to afirst exemplary leak test showing the output data of five of the sixteensensors used in the leak test;

[0030]FIG. 12 is sensor output data of the sensors in a leak testingapparatus showing the linear relationship of the average concentrationsof tracer gas measured by all of the sensors in a sensor array as afunction of time;

[0031]FIG. 13a shows a plurality of example sensor icon overlaid on apicture of a part under test;

[0032]FIG. 13b shows the sensor icons of FIG. 13a and an example of aleak graphic overlaid on a picture of a part under test to provide avisualization cue of a leak emanating from the part under test at theposition of the leak graphic;

[0033]FIG. 14 is a diagrammatic representation of a dual mode sensorapparatus configured to detect the presence of a tracer gas;

[0034]FIG. 15 is a diagrammatic representation of a sensor apparatusconfigured to detect the presence of a tracer gas and to provide anoutput signal to a remote device;

[0035]FIG. 16 is a diagrammatic representation of a sensor apparatusconfigured to be a stand alone leak detector;

[0036]FIG. 17 shows an electronic schematic of a dual mode sensorapparatus of the present invention;

[0037]FIG. 18 is a perspective view of a thermal conductivity sensoryelement for use in a sensor apparatus, such as the sensor apparatus ofFIGS. 14-17;

[0038]FIG. 19 is a first perspective view of an exterior of the sensorapparatus of FIG. 17 incorporating the thermal conductivity sensor ofFIG. 18;

[0039]FIG. 20 is a second perspective view of the exterior of the sensorapparatus of FIG. 17 showing an indicator and an I/O interface;

[0040]FIG. 21 is a flowchart of a first exemplary embodiment of sensorsoftware for the sensor apparatus;

[0041]FIG. 22 is a flowchart of a first exemplary interrupt routine ofthe sensor software of FIG. 21;

[0042]FIG. 23 is a flowchart of a second exemplary interrupt routine ofthe sensor software of FIG. 21;

[0043]FIG. 24 is a flowchart of a third exemplary interrupt routine ofthe sensor software of FIG. 21;

[0044]FIG. 25 is a first perspective view of an exterior of a sensorapparatus showing a sensing element accessible from the exterior;

[0045]FIG. 26 is a second perspective view of the exterior of the sensorapparatus of FIG. 25 showing an I/O interface; and

[0046]FIG. 27 is a diagrammatic representation of the sensor apparatusof the present invention incorporated as sensors in a component such asan automobile.

DETAILED DESCRIPTION

[0047] While the invention is susceptible to various modifications andalternative forms, exemplary embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

A Leak Detection Apparatus

[0048] Referring to FIG. 1, a diagrammatic representation of a leaktesting apparatus 100 according to the present invention is shown. Leaktesting apparatus 100 includes a test region 102, a plurality of sensors106 (of which sensors 106 a and 106 b are shown for illustration), acontroller 108, and an indicator 110. Although only two sensors, 106 aand 106 b are shown in FIG. 1, it is contemplated that plurality ofsensors 106 includes two, three or more sensors. Test region 102 isconfigured to receive a part under test 112 having at least a firstpotential leak region 114. Example potential leak regions include weldregions and joints. However, in one example the entire surface of a partunder test or a portion thereof may be tested for potential leaks andtherefore the entire surface or portion thereof may be considered apotential leak region. In one example, test region 102 includes at leastone fixture (not shown) configured to hold part under test 112 andconfigured to position the plurality of sensors 106 relative topotential leak region 114 of part under test 112. In another embodiment,test region 102 further includes a pressure chamber (not shown). Thepressure chamber being configured to pressurize a volume of air aroundpart under test 112.

[0049] In the illustrated embodiment, controller 108 includes a computer116 and a programmable logic controller (PLC) 118. Computer 116 isconfigured to process data received from the plurality of sensors 106,identify the location of a leak, provide a signal to indicator 110 ofthe location of the leak, and to provide for the ability of the leakdata to be stored for future analysis. In another embodiment, computer116 is further configured to quantify the leak rate of the leak and toprovide a signal to indicator 110 of the leak rate. An exemplarycomputer 116 is an EMAC Industrial computer available from EMAC, Inc.located at P.O. Box 2042, Carbondale, Ill. 62902.

[0050] PLC 118 is configured to control the physical motions of leaktesting apparatus 100. An exemplary PLC 118 is a Model No. SLC 5/05available from Allen Bradley through Rockwell Automation located at USBank Center, 777 East Wisconsin Avenue, Suite 1400 Milwaukee, Wis.53202. In one example, PLC 118 is configured to actuate components, suchas cylinders, to secure part under test 112 in the corresponding fixtureor fixtures of test region 102 configured to secure part under test 112and to position plurality of sensors 106 a and 106 b proximate topotential leak region 114. PLC 118 is further configured to control thefilling and evacuating of the part under test 112 with a tracer gas. Inan alternative embodiment PLC 118 is configured to control the filingand evacuating of the pressure chamber of test region 102 with a tracergas. The use of a PLC to control the filing and evacuating of the partunder test with a tracer gas, such as PLC 118, is well known in the art.

[0051] PLC 118 is further connected to a human-machine interface (HMI)119. HMI 119 provides an exemplary interface for the operator of leaktesting apparatus 100 to input parameter values to leak testingapparatus 100, such as a setpoint or leak rate which corresponds to anunacceptable leak in the part under test and/or a test timer value tocontrol the length of a test cycle for part under test 112. An exemplaryHMI is a Panelview standard terminal from Allen Bradley through RockwellAutomation located at US Bank Center, 777 East Wisconsin Avenue, Suite1400 Milwaukee, Wis. 53202. In the illustrated embodiment HMI 119 islinked to controller 108 through a network, such as network 120discussed below. In an alternative embodiment, HMI 119 is directlyconnected to controller 108.

[0052] In another embodiment PLC 118 is provided parameter values acrossa network, such as network 120, from from computer 116 or from a remotecomputer (not shown). In a further embodiment PLC 118 is providedparameter values from a computer readable media (not shown) removablycoupled to PLC 118 or computer 116 or a remote computer (not shown).

[0053] In one embodiment of leak testing apparatus 100, PLC 118 isfurther configured to perform an initial knock-out or gross leak test onpart under test 112, such as a pressure decay test. It is well known inthe art to use a PLC, such as PLC 118, to perform a pressure decay teston a part under test. If part 112 fails the gross leak test then thepart under test 112 does not need to be tested with the more accuratetracer gas or fine leak test described below unless it is desired topin-point the location of the gross leak. In one variation, the grossleak test, such as the pressure decay test is conducted simultaneouslywith the fine leak test. When a pressure decay test and the fine leaktest are conducted simultaneously, the pressure decay test uses a gascontaining the tracer gas.

[0054] In the illustrated embodiment, computer 116 and PLC 118 arelinked together through network 120. Network 120 is configured to permitcomputer 116 and PLC 118 to share information. Exemplary networksinclude wired networks, wireless networks, such as an RF network, an IRnetwork, or a cellular network, local area networks, such as an Ethernetnetwork or a token ring network, wide area networks, a controller areanetwork (CAN), connections to the Internet or an Intranet, a RS232connection, an RS485 connection, or other suitable networks or methodsof connecting computer 116 and PLC 118. Computer 116 and PLC 118 can beconnected to additional devices across network 120, such as remotecomputers (not shown) in quality control or to control devicespositioned at various stations in the manufacturing process of partunder test 112. As such, feedback can be instantly provided to qualitycontrol personnel or manufacturing personnel concerning the location ofleaks in rejected parts and of any correlation between the leaklocations of the rejected parts.

[0055] In an alternative embodiment, controller 108 is comprised of asingle computer, such as computer 116 which is configured to perform theabove-described functions of both computer 116 and PLC 118. In oneexample, HMI 119 is a touch screen, a light pen, a mouse, a roller ball,or a keyboard.

[0056] As stated earlier, for a fine leak test, controller 108 isconfigured to provide a gas including a tracer gas to either an interiorof part under test 112 or an exterior of part under test 112. It is wellknown in the art to seal a part under test so that the tracer gas isretained on either the interior or exterior of part under test 112 inthe absence of a leak in part under test 112. If the tracer gas isprovided to the interior of the part under test then test region 102does not require a pressure chamber while if the tracer gas is providedto the exterior of the part under test 112 then the test region 102includes a pressure chamber (not shown) to permit the exterior of thepart under test 112 to be pressurized.

[0057] The tracer gas is introduced to either the interior or theexterior of part under test 112 such that the interior or exteriorincluding the tracer gas is at a higher pressure relative to the otherof the interior or exterior not including the tracer gas. Therefore, apressure difference is created between the interior of part under test112 and the exterior of part under test 112, the higher pressure regioncorresponding to the region containing the tracer gas. As such, if partunder test 112 includes a leak, the tracer gas will emanate or flow fromthe higher pressure region to the lower pressure region. In one examplethe tracer gas is helium. In another example the tracer gas is hydrogen.

[0058] Leak testing apparatus 100 is configured to detect the presenceof a leak in part under test 112, as indicated by the presence of thetracer gas in the lower pressure region. Leak testing apparatus 100 isfurther configured to run a leak test whereby part under test 112 ismonitored for leaks for a time period corresponding to a value of thetest timer provided to PLC 118. As shown in FIG. 1, sensors 106 areplaced proximate to potential leak region 114. As stated before it iscontemplated to position more than two sensors 106 proximate to region114. Sensors 106 are connected to controller 108 and are configured toprovide a sensing signal, representative of the detection of the tracergas. In one example the sensing signal is proportional to theconcentration of the tracer gas. In the illustrated embodiment, sensors106 a and 106 b are connected to controller 108 over a network 122,network 122 being generally similar to network 120, such that sensors106 a and 106 b each generate a sensing signal and provide the sensingsignal to controller 108 across network 122 as a network message or datapacket. In one example network 122 and network 120 are portions of thesame network. In an alternative embodiment, the sensors 106 areconnected to controller 108 directly such that controller 108 receives asensing signal from each sensor as a direct input, such as an analogsignal.

[0059] Controller 108 is configured to receive the sensing signals fromsensors 106 and to determine if the sensing signals indicate that a leakis present in part under test 112. As explained in more detail below,the location of the leak can be deduced by monitoring the individualsensing signals from sensors 106. Further, as explained in detail below,if the sensors define an area of containment or accumulation volume theleak rate of leak can be deduced or quantified by monitoring theaggregate sensing signals, such as the sensing signals from both sensors106.

[0060] Indicator 110 is connected to controller 108 and configured toprovide an indication signal to an operator of leak testing apparatus100 of the presence and location of a leak in part under test 112.Controller 108 is configured to provide a leak detection signal toindicator 110 in response to at least one of sensors 106 a and 106 bdetecting the presence of the tracer gas. Further, the leak detectionsignal of controller 108 can be provided to other devices such as aremote controller (not shown). The leak detection signal includinginformation representative of the location of the leak and/orinformation related to the leak rate of the leak.

[0061] In the illustrated embodiment indicator 110 is directly connectedto controller 108. In another embodiment, indicator 110 is linked tocontroller 108 over a network, such as network 120. Example indicationsignals include a signal to a network device containing the location ofthe leak, an audio message, a visual text message of the location of theleak, or a visual image of the part under test with a leak graphicplaced at the location of the leak. In one embodiment, indicator 110 isfurther configured to provide an indication of the leak rate of theleak. The indication of the leak rate can be included in the same signalas the location of the leak or sent in a second indication signal.

[0062] Referring to FIG. 2, a leak testing apparatus 100′ is shown in aconfiguration for monitoring a part under test 212 having at least twopotential leak regions 214 a and 214 b. Leak testing apparatus 100′ isgenerally similar to leak testing apparatus 100. As such, like numeralsare used for components that are common to both leak testing apparatus100 and leak testing apparatus 100′. As shown in FIG. 2, a first sensorarray 224 a comprising a plurality of sensors such as sensors 106 a and106 b is positioned proximate to a first potential leak region 214 a anda second sensor array 224 b comprising a plurality of sensors such assensors 206 a, 206 b, 206 c, 206 d, 206 e, 206 f, and 206 g ispositioned proximate a second potential leak region 214 b. Sensors 206a-g are generally identical to sensors 106 a and 106 b. Each sensorarray 224 a and 224 b is connected to controller 108. As stated abovethe sensors are connected to controller 108 either through a network,such as network 122 or directly.

[0063] In one embodiment sensor arrays 224 a and 224 b simply denote thesensor grouping, sensors 106 a and 106 b and sensor 206 a-g,respectively. In another embodiment sensor arrays 224 a and 224 bcorrespond to network devices configured to relay network traffic fromthe respective sensors to other network components, such as controller108. In one example, sensor arrays 224 a and 224 b are network routers.In yet another embodiment, sensor arrays 224 a and 224 b are controllersand are configured to receive data from the respective sensors and tocompile network messages to other network devices based on the datareceived from the respective sensors. In one example the respectivesensors are linked to the sensor array controllers through a networksimilar to network 122. In another example the respective sensors aredirectly connected to the sensor array controllers and provide an analogoutput. The network messages compiled by the sensor array controller maybe the relaying of signals from the respective sensors, an indication ofa leak location, or an indication of the leak rate of a leak.

[0064] Although the present invention may be practiced with a singlesensor positioned proximate to region 214 a and a single sensorpositioned proximate to region 214 b, the more sensors that arepositioned proximate to either potential leak region 214 a or 214 b thegreater the accuracy of leak detection apparatus 100′ in determining thelocation of the leak and/or the quantification of the leak rate. Assuch, it is preferred to connect sensors 206 a-g, 106 a and 106 b tocontroller 108 through a network because such a connection allows formany sensors to communicate with controller 108 without requiring thatcontroller 108 to have a multitude of data inputs, only access to anetwork.

[0065] Referring to FIG. 3, an exemplary sensor array 130 includes aplurality of sensors 132 a-l. Sensor array 130 is configured to be usedwith leak testing apparatus 100 or with leak testing apparatus 100′. Asshown in FIG. 4a, each sensor 132 a-l includes a sensing element ortransducer 134 a-l. In a preferred embodiment sensors 132 a-l areconfigured to interface with a network, such as a Controller AreaNetwork (CAN) network or an RS-485 network. An exemplary sensor for useover either a CAN network or an RS-485 is sensor 300 shown in FIGS.14-24 below. As explained below, in connection with sensor 300, sensingelement or transducer 134 a-l of sensor 132 a-l is configured to detectthe presence of the tracer gas when the tracer gas is in contact withsensing element or transducer 134 a-l. Although sensor 300 as describedbelow is capable of functioning in both an analog mode and a networkmode, it is to be understood that sensors 132 a-l in the preferredembodiment need only to be capable of functioning in the network modeand further only need to be configured for one network, such as eitherRS-485 or CAN. In alternative embodiments, sensors 132 a-l areconfigured for two or more networks.

[0066] Sensors 132 a-l of sensor array 130 are affixed in a fixture 133such that sensor array 130 is easy to position relative to a potentialleak area of a part under test, such as a weld 134 of torque converter136 shown in FIGS. 3, 5 and 6. Fixture 133 is configured to positionsensors 132 a-l proximate to weld 134 of torque converter 136 in arepeatable fashion such that sensor 132 a is always placed next toportion 138 of weld 134. As such, if a leak is present in portion 138 ofweld 134 in a first torque converter 136 and a subsequent torqueconverter 136 the same sensor, sensor 132 a, will be denoted as beingproximate to the leak.

[0067] As shown in FIGS. 3, 4a, 4 b, 5 and 6, fixture 133 is configuredto define in cooperation with part 134 an interior region oraccumulation volume 140 (shown in FIG. 6) wherein any emanating tracergas from an interior region 142 of part 136 through a leak such as leak144 in weld 134 will be collected. The emanating tracer gas is collectedwithin interior region 140 such that the change in concentration of thetracer gas over time may be monitored to quantify the leak rate of theleak. In one example, interior region 142 is not a sealed region, inorder to prevent a pressure buildup in interior region 142 and hence aslowing of leak 144 which could lead to an inaccurate calculation of thecorresponding leak rate.

[0068] In an alternative embodiment, the fixture for securing the sensorarray supports the sensors and positions the sensors repeatably inrelation to the potential leak region. However, the fixture does notdefine an interior region wherein emanating tracer gas collects. Assuch, the fixture does not permit an accurate estimate of the leak rateonly an indication of the location of the leak relative to the potentialleak region.

[0069] Referring to FIG. 6, sensor 132 f is positioned proximate to leak144. As such, sensing element 134 f will detect the presence of thetracer gas emanating from leak 144 before sensing element 134 a ofsensor 132 a will detect the presence of the tracer gas. Further, overtime sensor 132 f will have a maximum response compared to sensor 132 ameaning that sensor 132 f will detect a higher concentration of thetracer gas than sensor 132 a. As explained below, one or both of thesefacts is used to determine the location of leak 144. Further, asexplained below the summation and average of the response of all sensors132 a-l is used to determine the leak rate associated with leak 144 whenthe geometry of fixture 133 is such that the tracer gas emanating fromleak 144 is generally retained in interior region 140.

[0070] Referring to FIGS. 7-10, an exemplary embodiment of a leaktesting software 600 is shown. Leak testing software 600 is configuredto be executed by controller 108 in association with a fine leak test.For example, for the testing of part 136 of FIGS. 3, 5, and 6, software600 is configured to associate sensor array 130 and sensors 132 a-lrelative to test part 136, to monitor signals provided by sensors 132a-l over a network, such as network 122, and to provide an indication ofthe location of leak 144 and/or to provide an indication of the leakrate associated with leak 144. In one example, controller 108 as a leakdetection signal provides the indication of the location of leak 144and/or the leak rate of leak 144. It is contemplated that software 600is configured to monitor multiple sensor arrays. In the illustratedembodiment shown in FIGS. 7-10, leak testing software 600 is executed bycomputer 116 and receives information from and sends information to PLC118. In an alternative embodiment, leak testing software 600 ispartially executed by computer 116 and partially executed by PLC 118. Inyet a further alternative embodiment at least a portion of thefunctionality of software 600 is provided as firmware. In anotheralternative embodiment, software 600 is executed by a remote computerand commands are provided to controller 108 over a network, such asnetwork 120.

[0071] In one embodiment, software 600 is available as one or more fileson a portable computer readable media, such as a diskette, a CD-Rom, aZip disk, a tape, a memory card, or a flash memory card. Software 600 inone example includes an installation program configured to load software600 on computer 116 and/or to configure software 600. In an alternativeembodiment, software 600 and/or an installation program is availableacross a network as one or more downloadable files.

[0072] Referring to FIG. 7, leak testing software 600 includes a setupportion 602 configured to allow an operator to set a variety ofparameters related to a particular job, such as the testing of aparticular part under test, for instance part 136, and a operatorportion 604 configured to be used by the operator preparing to leak testa part. Operator portion 604 is configured to load the parameters setfor a particular part under test and to execute a testing routine 656 totest a first part for a leak.

[0073] Referring to FIG. 8, an exemplary setup portion 602 of software600 is shown. As represented by block 606, at least a first picturerepresentative of the part to be tested is loaded. The picture is usedto provide a visual indication to the operator of the location of theleak. In a first example, the picture corresponds to a still image of aphysical part. In a second example, the picture corresponds to a viewproduced from an electronic database of the part such as a CAD softwarepackage. In a third example, the picture corresponds to a threedimensional solid model of the part produced from an electronic databasesuch as a CAD software package.

[0074] As represented by block 608, the operator places a representationof a sensor, such as sensor 132 a, on the picture of the part to betested. In one embodiment the representation of the sensor is a sensoricon, see FIG. 13a for an example sensor icon such as sensor icon 135 a.The sensor icon shown in FIG. 13a is a triangular shape. However, it iscontemplated that the sensor icon could be a variety of shapes and couldinclude text such that a sensor number and/or sensor name is displayed.The location of sensor 132 a on the picture corresponds to the locationof the physical sensor 132 a relative to part 136 during the testing ofpart 136. However, updating the location of sensor 132 a on the picturedoes not move the location of sensor 132 a on the physical part. Thelocation of sensor 132 a on the picture is simply a representation ofthe location of sensor 132 a on the physical part. The operator thenupdates the information related to sensor 132 a, as represented by block610. Example sensor information to be updated includes a name for sensor132 a, a network id for sensor 132 a, sensor position data, which sensorgroup or array 130 sensor 132 a is associated with, and a displaypriority for sensor 132 a or the picture currently displayed. Thedisplay priority is a parameter associated with the preferred view toshow a leak emanating from sensor 132 a. In the case of a picture thedisplay primary parameter indicates the default view to use duringoperator portion 604.

[0075] Software 600 queries whether additional sensors are to bedisplayed on the current picture of the part to be tested, asrepresented by block 612. If additional sensor locations are visible inthe current picture, the operator selects yes and repeats the aboveprocess for the additional sensors. If additional sensors are notvisible in the current picture, the operator should select no whichleads software 600 to query whether additional pictures of the part tobe tested are to be loaded, as represented by block 614. If additionalpictures are to be loaded, the operator selects yes and software 600will loop back to block 606. Otherwise, the operator is prompted to savethe sensor mapping file corresponding to the part to be tested, asrepresented by block 616. The sensor mapping file includes theinformation entered during the setup portion 602. In one example, thesensor mapping file is a text file which includes at least references tothe pictures of the part to be tested, the sensors included on eachpicture, the sensor positions for each picture and the sensor parametersfor each picture.

[0076] Turning to FIG. 9, operator portion 604 of software 600 is shown.As represented by block 620, the operator upon initiating operatorportion 604 enters or selects the location of the directory containingthe sensor mapping file corresponding to the current part under test,such as part 136. If the operator does not select a proper path theoperator is again required to enter or select the directory, asrepresented by block 622. Otherwise, if a proper path is selected, theoperator next selects the correct sensor mapping file 616, asrepresented by block 624.

[0077] The sensor mapping file is loaded into a memory of controller 108and the operator is presented with a list of pictures of the part undertest contained within the sensor mapping file, as represented by block626. The operator selects a picture from the list and the selectedpicture along with the sensor icons 135 are displayed on a correspondingdisplay, as represented by blocks 628 and 630. By having the operatorselect a picture for viewing, a visual check can be done by the operatorto insure that the selected sensor mapping file corresponds to the partto be tested.

[0078] At this point the operator can make changes to the sensorinformation or sensor placement or proceed to begin testing, asrepresented by block 632. If updates are required the operator selectsthe sensor to be updated, as represented by block 634. The operator canupdate the placement of a selected sensor by manually inputting newposition information or by moving the corresponding sensor icon 135relative to the picture of the part. However, the user is only changingthe position of the sensor on the picture not the actual physical sensorlocation. Either way the new sensor position is received and the sensortable is updated, as represented by blocks 636, 638, and 640. Further,the operator can update the sensor information, such as displaypriority, sensor name, or sensor network id, as represented by blocks642, 644, and 646. In one example, the sensor information must beupdated when a broken sensor is replaced with a new sensor having adifferent network id.

[0079] The operator can now select another sensor and update either thesensor position or sensor information associated with that sensor, asrepresented by block 648. If an additional sensor is selected the abovedescribed process related to blocks 636, 638, 640, 642, 644, and 646 isrepeated. Once the updates have been made to the positions of thesensors or the sensor information, the operator must either save thechanges to the sensor mapping file or discard the changes, asrepresented by block 650. If the changes are saved, software 600 querieswhether to initiate a testing routine, as represented by blocks 652,654, and 656. If the changes are discarded the operator is againpresented with the option of updating the sensor position or sensorinformation, as represented by block 632.

[0080] As represented by blocks 654, 656, 658, 660, and 662, once theupdates have been made to the displayed picture, the operator can eitherbegin the testing routine, block 656, exit the program, block 660,select a new sensor mapping file, blocks 662 and 620, or select anadditional picture associated with the current sensor mapping file,block 662, 626, and 628. The operator, in one example would select anadditional picture associated with the sensor mapping file to update thesensor placement or sensor information of a sensor not visible in theprevious displayed picture. Further, in one example, the softwarerecognizes sensor position changes or sensor information changes in afirst picture and updates the corresponding sensor position or sensorinformation for the additional pictures including the sensor.

[0081] Referring to FIG. 10, an example testing routine 656 is shown. Asrepresented by blocks 664 and 665, when a testing routine is initiatedthe selected sensor mapping file is loaded, block 664, and theassociated part images or pictures are loaded, block 665. One of thepart images has a parameter value designating that part image as adefault part image. The default part image is shown on the display, asrepresented by block 668. The display of a default image provides avisual cue to the operator that software 600 has loaded the correctsensor mapping file and the corresponding part images.

[0082] Software 600 waits for a start test signal from the PLCindicating that the part under test is ready for testing, as representedby block 670. In one example, the signal from the PLC corresponds to thesituation wherein part under test 136 has been properly positioned intest region 102, sensors 132 are all in the correct positions, thetracer gas has been properly introduced and the pressure differencebetween the exterior and interior of the part under test has beenestablished. Once the start test signal is received from PLC 118, acommand is issued to all sensors 132 to monitor for the presence of thetracer gas, as represented by block 672, and a test timer is initiated,as represented by block 674. The test timer defines the length of thetest for part 136. If a leak is not detected in part 136 during thelength of the test timer part 136 is approved. In one example of testingroutine 656, testing routine either upon the detection of a leak orexpiration of the test timer is reset to begin testing on a second part,wherein the second part is generally identical to part 136. As such,once the operator enters testing routine 656, the operator does not haveto cycle through the additional prompts of operator portion 604, such asblocks 620, 624 and 628 before testing the second part.

[0083] As represented by block 676, the software monitors network 122 todetermine if data is received from a sensor 132 or other component onnetwork 122. If data is received across network 122, the determinationis made whether the data corresponds to a detection of the tracer gas,as represented by block 678. In one example, the determination isdependent on whether the amount of tracer gas detected exceeds athreshold value set by a parameter in the sensor mapping file. If thedata does not corresponds to the detection of the tracer gas, the testtimer is checked to determine if the testing procedure is complete, asrepresented by block 680. An example instance of data not correspondingto the detection of the tracer gas includes sensor status data, such assensor 132 is operating properly or that an error has occurred.

[0084] If the data does correspond to the detection of the tracer gas,then the data and subsequent data is analyzed, as represented by block685. The data is analyzed to determine the location of the leak, asrepresented by block 686, a localization routine. In one embodiment, thedata is further analyzed to determine the rate of the leak, asrepresented by block 688, a leak rate routine. Leak rate routine 688 isexecuted generally simultaneous with localization routine 686. Bothlocalization routine 686 and leak rate routine 688 provide informationto generate an indication of a leak in part 136, such as a visualizationof the leak on a picture or image of the test part to easily allow theoperator to note the location and size of the leak. For example, a leakgraphic 137 as shown in FIG. 13B to represent the detection of a leak bysensor 132 f. Additional indications of the leak include a signal sentby controller 108 to a remote device, such as a computer in qualitycontrol or in the manufacturing area, a visual text message on the HMIunit associated with PLC 118, an audible alarm, or a visual cue such asa flashing light.

[0085] Localization routine 686 determines the location of the leak byfinding the sensor which is detecting the largest concentration of thetracer gas, as represented by block 690. The location of the leak iscorrelated to the location of this sensor, as represented by block 692.The picture of part 136 that provides the optimal viewing of thelocation of the leak is automatically selected and displayed along withan indication of the leak location, as represented by block 694. Thepicture to display is based on the display preference set for the sensorin the sensor mapping file. In a first example, flashing thecorresponding sensor icon or changing the color or other attribute ofthe corresponding sensor icon is a visual cue of the leak location. In asecond example, as shown in FIG. 13B, the leak location is shown by leakgraphic 137 representing the emanating of the tracer gas from the leaklocation. In a further example, the leak graphic of FIG. 13B is ananimated graphic such that the graphic simulates gas emanating from theleak location. In yet a further example, the leak graphic flashes tofurther indicate the location of the leak. Both exemplary sensor iconsand leak graphics are shown in FIG. 13B.

[0086] In an alternative embodiment, the location of the leak isdetermined by the sensor which was the first to detect the tracer gas.In a further alternative embodiment, the location of the leak isdetermined by the sensor which is the first to detect a presence of thetracer gas above a threshold level. In yet a further alternativeembodiment, wherein two adjacent sensors both report similar detectionsof the tracer gas, the location of the leak is determined to be betweenthe location of the two adjacent sensors, such as halfway between thesensors or closer to a first sensor of the adjacent sensors due to arelative weighting of the values reported by each sensor.

[0087] It is further contemplated that the part under test might includemore than one leak. Multiple leaks may occur in the same potential leakregion or in differing potential leak regions. When sensors in differingpotential leak regions each report the detection of a leak, the abovelocation routine 686 and the rate routine 688 are conducted for eachregion. In the instance wherein multiple leaks are in the same potentialleak region, the software recognizes multiple leaks by the detection ofthe tracer gas by two non-adjacent sensors giving rise to a leakcondition. For instance, two non-adjacent sensors each record a localmaximum of tracer gas concentration or two non-adjacent sensors eachrecord the presence of the tracer gas before the intervening sensorsrecord the presence of the tracer gas.

[0088] In the case of multiple leaks it is possible to show multipleimages of the part under test on the display at the same time, such as asplit screen. The multiple views of the part under test is requiredbecause the preferred view of each sensor might be a different image orat least one of the sensors corresponding to a leak is not visible inthe preferred image of the other sensor.

[0089] Leak rate routine 688 is configured to determine the leak rate ofthe identified leak. As represented by block 696, for the sensor arraydetecting a leak the readings from each sensor associated with thatsensor array is summed and then averaged. Further, this average sensorreading is monitored over time and an average rate of change in theaverage sensor reading is calculated, as represented by block 698. In atypical leak testing situation the testing cycle and leak size are suchthat the rate of change of average sensor readings is generally linear.As such, determining the slope of a line approximating the averagesensor readings over time approximates the leak rate.

[0090] The rate of change in the average sensor readings is scaled toleak rate units, as represented by block 700. In one example, thescaling is accomplished by comparing the determined slope rate from theblock 698 and slope rates for known leaks taking into account theaccumulation volume of the fixture containing the sensors, such asfixture 133. The rate of change in the average sensor readings isdirectly proportional to the leak rate of the leak and inverselyproportional to the volume of the accumulation volume. Further, the leakrate is displayed on the part picture or image along with the leaklocation determined by the localization routine 686. In one example, theleak rate is shown as a numeric value proximate to the leak location. Inanother example, the leak rate is simulated by the selection of the leakgraphic to use to simulate the leak (see FIG. 13B). For example, agraphic showing a large leak emanating from the leak location is usedfor a high leak rate while a graphic showing a small leak emanating fromthe leak location is used for a small leak rate.

[0091] Referring to FIGS. 11 and 12, example sensor output correspondingto the leak testing of part 136 with leak testing apparatus 100 isshown. For the example shown in FIGS. 11 and 12, a known leak 144 wasintroduced into the part in the vicinity of potential leak region 134.Known leak 144 was created by in part 136 by inserting a calibrated leakstandard through part 136. Further, known leak 144 was sized to have aknown leak rate equal to 0.1 scc/min (standard cubic centimeters perminute). In order to test leak testing software 600, the tracer gas isprovided to interior 142 of part 134 through a valve such that theresponse time of system 100 can be determined.

[0092]FIG. 11 provides the individual sensor readings over time for fiveof the sixteen sensors positioned proximate to the potential leakregion. The five selected sensors correspond to the four sensors closestto leak 144 and a sensor distal to leak 144. It should be noted thatsixteen sensors exceeds the twelve sensors 132 a-l illustrated in FIGS.3-5. As such, the results shown in FIG. 11 should be able to provide amore accurate location of leak 144 than the results of the twelve sensorarrangement shown in FIGS. 3-5.

[0093] Looking at FIG. 11, the sensor denoted as sensor 13 shows thefirst detection of the tracer gas and also exhibits the highest recordedconcentration of the tracer gas as represented by data series 160. Thesensors denoted as sensors 12, 14, and 15 are proximate to sensor 13 anddenoted by data series 162, 164, and 166, respectively. Each of sensors12, 14, and 15 detect the presence of the tracer gas slightly aftersensor 13 and each of sensors 12, 14, and 15 detect lower concentrationsof the tracer gas than sensor 13. As such, the location of leak 144 isproximate to sensor 13. However, it should be noted that the strongresponse of sensor 14 and the similar responses of sensors 12 and 15suggests that the leak is positioned roughly halfway between sensors 13and 14. Further, data series 168 corresponding to the sensor denotedsensor 5 which is distally positioned relative to sensor 13 is includedto demonstrate that sensors farther from the location of leak 144 lag inthe detection of the tracer gas and the measured concentration of thetracer gas over sensors that are more proximate to leak 144 such assensors 12, 14, and 15.

[0094] Referring to FIG. 12, two data series 170 and 172 are shown. Dataseries 170 corresponds to the turning on of leak 144, represented byportion 174 of series 170, and the turning off of leak 144, representedby portion 176 of data series 170. Leak 144 is turned on by introducingtracer gas to interior 142 of part 136 through a valve and is turned offby shutting the valve. Data series 172 corresponds to the average valueof the concentration of tracer gas for all of the sensors in the sensorarray over time. Looking at FIG. 12, the response time of the system isvery good. Within approximately three seconds the linear region 180 ofdata series 172 is developing suggesting that for a leak the size ofknown leak 144 the system is capable determining the leak rate withinapproximately three to five seconds. Further, the region 180 of series172 is very linear, suggesting that the slope of region 180 will providea good approximation of the leak rate of leak 144.

[0095] Returning to FIG. 10, the test timer takes precedence overlocalization routine 686 and rate routine 688. As such, when the testtimer has expired, a stop command is issued to the sensors, asrepresented by block 682. Further, a final leak rate is calculated andsent to the PLC, as represented by block 684. Alternatively the finalleak rate is made available to additional devices on network 122.

Sensor Apparatus for the Detection of a Gas

[0096] Referring to FIG. 14, a sensor apparatus 300 is shown. Sensorapparatus 300 is configured to detect the presence of a gas, such as atracer gas and to provide an appropriate output to communicate thedetection of the presence of the gas. In a first application sensorapparatus is configured to detect the presence of a tracer gas, such ashelium or hydrogen, in a leak testing application. In a secondapplication sensor apparatus 300 is configured to detect the presence ofa gas, such as helium or hydrogen, and to be incorporated into thedesign of a component as a safety sensor, example components includesautomobiles, trucks, aircraft, boats, and subsystems thereof such asfuel systems, exhaust systems, passenger cabin systems and cargosystems.

[0097] Sensor apparatus 300 in one example is capable of detectingconcentrations of Helium, a tracer gas, in the range of about 0 ppm(parts per million) to about 5000 ppm and having a resolution of about25 ppm. In another example sensor apparatus 300 is capable of detectingconcentrations of Helium, a tracer gas, in the range of about 0 ppm toabout 5000 ppm and having a resolution of about 5 ppm. In yet anotherexample, sensor apparatus 300 is capable of detecting concentrations ofHelium exceeding about 5000 ppm.

[0098] Sensor apparatus 300 is capable of operating in one of two modesof operation. In a first mode of operation, sensor apparatus 300 is aself-contained sensor apparatus or a self-contained leak testingapparatus and provides an indication to the operator of the detection ofthe gas, such as the tracer gas, by sensor apparatus 300. In a secondmode of operation, sensor apparatus 300 provides a signal to a remotecontroller, the signal including information related to the detection ofthe gas such as the tracer gas by sensor apparatus 300. Both modes ofoperation are described in detail below. In one example of the secondmode of operation, sensor apparatus 300 is a networkable sensor thatprovides a signal to the remote controller over a network.

[0099] When sensor apparatus 300 is capable of operating in both modesof operation, although not necessarily both modes at the same time,sensor apparatus 300 is a dual mode sensor apparatus or a dual mode leakdetection apparatus. However, it is within the scope of the inventionthat sensor apparatus 300 is configured to only operate in either thefirst mode of operation, see generally sensor apparatus 300′ in FIG. 15,or the second mode of operation, see generally sensor apparatus 300″ inFIG. 16.

[0100] Referring back to FIG. 14, sensor apparatus 300 is a dual modeleak detection apparatus and comprises a controller 302 connected,either directly or through additional components, to a sensor 304, apower supply 306, an indicator 308 and an I/O interface 310. Controller302, sensor 304, power supply 306, and indicator 308 are enclosed in ahousing 312. However, indicator 308 is at least viewable from theexterior of housing 312 and I/O interface 310 is accessible from theexterior of housing 312. Further, a sensing element or transducer 314 ofsensor 304 is accessible from the exterior of housing 312 and ispositioned generally proximate to the exterior of housing 312. As such,sensor apparatus 300 does not require that the gas to be tested for thepresence of the tracer gas be drawn to or past an internal sensingelement.

[0101] As explained in more detail below, sensor 304 is configured todetect the presence of a gas, such as a tracer gas, and to provide asensing signal to controller 302, the sensing signal being indicative ofthe presence or absence of the tracer gas and the amount or magnitude oftracer gas detected. In one example the sensing signal is proportionalto the concentration of the detected tracer gas. Power supply 306 isconfigured to provide power to controller 302, sensor 304, indicator308, and/or I/O interface 310. Indicator 308 is configured to provide anindication to the operator of sensor apparatus 300 of the detection ofthe tracer gas and/or the amount of tracer gas detected. I/O interface310 is configured to provide an output signal to an external device, theoutput signal being representative of the detection or lack of detectionof the tracer gas and/or the amount of tracer gas detected. Furthersignals are also contemplated, such as an error signal or a sensorstatus signal. In one embodiment I/O interface 310 is configured to linksensor apparatus 300 to a network.

[0102] Controller 302 is configured to receive the sensing signal fromsensor 304 and to analyze or make additional determinations based on thesensing signal from sensor 304. Further, controller 302 is configured toprovide an indication signal to indicator 308, the indication signalbeing representative of the detection or lack of detection of the tracergas and/or the amount of tracer gas detected, or controller 302 isconfigured to provide an I/O signal to I/O interface 310, the I/O signalbeing representative of the detection or lack of detection of the tracergas and/or the amount of tracer gas detected, or controller 302 isconfigured to provide both an indication signal to indicator 308 and anI/O signal to I/O interface 310.

[0103] Referring to FIG. 15, sensor apparatus 300′ is shown. Sensorapparatus 300′ is generally similar to sensor apparatus 300 when sensorapparatus 300 is configured to operate in the second mode of operation.As such, like numerals are used for components that are common to bothsensor apparatus 300 and sensor apparatus 300′. Sensor apparatus 300′provides a signal to a remote controller (not shown), the signalincluding information related to the detection of the gas by sensorapparatus 300. In one example, sensor apparatus 300′ is configured to belinked to a network. As such, sensor apparatus 300′ is generally similarto sensor apparatus 300 expect that an indicator, such as indicator 308is not needed. In addition since sensor apparatus 300′ is connected to aremote controller through I/O interface 310, the power needed bycontroller 302 and sensor 304 can be provided through I/O interface 310instead of power supply 306. Alternatively, power supply 306 is includedin sensor apparatus 300′ in situations wherein a remote power supply isnot available, such as a wireless network. Further, the electronics ofsensor apparatus 300′, although generally similar to the electronics ofsensor apparatus 300 may be simpler at least due to the fact that sensor300′ does not need to supply an analog output, does not need to controlan indicator, and does not need to control a power supply.

[0104] Referring to FIG. 16, sensor apparatus 300″ is shown. Sensorapparatus 300″ is generally similar to sensor apparatus 300 when sensorapparatus 300 is configured to operate in the first mode of operationwhich corresponds to a self-contained sensor apparatus that provides anindication to the operator of the detection of the tracer gas by sensorapparatus 300. As such, like numerals are used for components that arecommon to both sensor apparatus 300 and sensor apparatus 300″ Sensorapparatus 300″ is generally similar to sensor apparatus 300 except thatan I/O interface, such as I/O interface 310 is not required. Further,the electronics of sensor apparatus 300″, although generally similar tothe electronics of sensor apparatus 300 can be simpler at least due tothe fact that the I/O interface is not required and the sensor does notneed to configure data and information for transmission over a network.

[0105] Referring to FIG. 17, one embodiment of a dual mode sensorapparatus 450 is shown. Sensor apparatus 450 is generally similar tosensor apparatus 300 and comprises a controller 452, a sensor 454, apower supply 456, an indicator 458, and an I/O member or interface 460each being generally similar to controller 302, sensor 304, power supply306, indicator 308, and I/O member or interface 310 of sensor apparatus300, respectively. Sensor apparatus 450 further comprises a programminginput 462, which includes a series of inputs 464 and is configured toprovide programming signals to controller 452 to modify theconfiguration of controller 452 or a parameter value stored in oraccessed by controller 452. In one example, programming unit 452 is usedto modify the network ID assigned to sensor apparatus 450 for use with aCAN network.

[0106] Sensor 454 of sensor apparatus 450 comprises a thermalconductivity sensor 466 and associated sensor circuitry 468 including anamplifier circuit 470. Thermal conductivity sensor 466 comprises asensing element or transducer 467 (shown in FIG. 18) such as a membrane(not shown) which is heated above ambient temperature, a measuringresistor or series of resistors 472 which measure the temperature of themembrane and an ambient temperature reference resistor or series ofresistors 474 which compensate for ambient temperature changes. As shownin FIG. 18 sensing element or transducer 467 is positioned on theexterior of sensor 466. In the illustrated embodiment, thermalconductivity sensor 466 is Model No. MTCS-2202, available from MicrosensSA located at Rue Jaquet-Droz 1, CH-2007 Neuchatel, Switerland.Alternate sensors include other suitable thermal conductivity sensors,acoustic wave transducers, optical feedback transducers, and othersuitable sensors capable of detecting the presence of the tracer gas.

[0107] Thermal conductivity sensor 466 measures the presence orconcentration of a tracer gas by comparing the resistance of measuringresistor 472, which is a measure of the temperature of the membrane, andthe resistance of reference resistor 474. Gases that have a lowerthermal conductivity than air cause a change in the surface temperatureof the sensor membrane and thus a change in the resistance of measuringresistor 472. As such, when the tracer gas is either helium or hydrogenthe presence of either helium or hydrogen adjacent the sensor membranecauses a change in the surface temperature of the sensor membrane andtherefore a change in the resistance of measuring resistor 472. Further,as the concentration of either helium or hydrogen adjacent the sensormembrane increases the resistance of measuring resistor 472 changesfurther.

[0108] The illustrated sensor circuitry 468 including amplifier 470 arerecommended by the manufacturer of thermal conductivity sensor 366,Microsens SA. In alternate embodiments, variations of sensor circuitryare contemplated. The output of amplifier 470 corresponds to the sensingsignal of sensor 454 and is provided to controller 452 over connection473. In one example the sensing signal is proportional to theconcentration of the detected tracer gas. The voltage value of theoutput of amplifier 470 is directly dependent on the resistance of themeasuring resistor 472. As such, the detection of either helium orhydrogen by measuring resistor 472 will result in a decrease of theoutput voltage of amplifier 470.

[0109] Power supply 456 comprises a power source 474 represented by thedesignation “5 VDC” and a voltage regulator 476. It should be noted thatthe designation “5 VDC” is shown multiple times in FIG. 17 forconvenience and that each instance is signifying a connection to powersource 474. Power source 474 in one exemplary embodiment is a portablepower source, such as a battery. Power source 474, in another exemplaryembodiment, is an external power source such as the output of an ACadapter connected to a standard electrical outlet. Further, power source474, in yet another embodiment, is an external power supply, whichprovides power to sensor apparatus 450 through I/O interface 460.

[0110] Voltage regulator 476 is configured to provide a generallyconstant voltage source to sensor 454 and controller 452. In theillustrated embodiment, voltage regulator 476 includes a circuit chip477 Model No. ADR421, which is available from Analog Devices located atOne Technology Way, P. O. Box 9106, Norwood, Mass. 02062-9106.

[0111] Controller 452, in the illustrated embodiment, includes aMicroConverter®, Model No. AduC834, available from Analog Devices.Controller 452 is a programmable device and includes a program memory(not shown) and a data memory (not shown). In the present inventioncontroller 452 is configured to receive the sensing signal from sensor454 over connection 473 and to analyze the sensing signal and/or makefurther determinations based on the sensing signal and the instructionsor program stored in controller 452. In one example, controller 452digitizes the sensing signal from sensor 454 and scales the sensingsignal to generate an output signal to provide to I/O interface 460. Inone example, the output signal is an analog singal generated by adigital to analog converter (D/A). In another example the output singalis a digital signal. Further, in one example, controller 452 generatesan indication signal to provide to indicator 458.

[0112] Indicator 458, in the illustrated embodiment comprises a firstlight emitting diode (“LED”) 478 and a second LED 480. LED 478 providesa light visible from the exterior of sensor apparatus 450 having a firstcolor, such as green. The green light of LED 478 is provided in responseto receiving a first indication signal from controller 452 correspondingto a power on state of sensor apparatus 450. As such, LED 478 provides avisual cue to the operator of sensor apparatus 450 that sensor apparatus450 is receiving power and is functional. In an alternative embodiment,the first LED is controlled by the controller to flash during a warm-upperiod of the sensor apparatus and to provide a steady signal when thesensor apparatus is ready for testing.

[0113] LED 480 provides a light visible from the exterior of the housingof sensor apparatus 450 having a second color, such as red. The redlight of LED 480 is provided in response to receiving a secondindication signal from controller 452 corresponding to the detection ofthe presence of the tracer gas by the sensor apparatus 450. As such, LED480 provides a visual cue to the operator of sensor apparatus 450 thatthe tracer gas has been detected. In a leak testing application LED 480provides a visual cue to the operator that the part under test has aleak in the vicinity of sensor 454. In another example LED 480 is abi-color LED, such as Model No. 591-3001-013 available from DialightCorporation located at 1501 Route 34 South Farmingdale, N.J. 07727. Thewavelength emitted by bi-color LED 480 is dependent on the signalprovided to LED 480. For instance, the wavelength can be varied from agenerally green wavelength to various shades of a generally orangewavelength and up to a generally red wavelength. As such, in one examplebi-color LED 480 provides a visual cue to the operator of sensorapparatus 450 of the concentration of detected tracer gas (green for lowconcentrations up to red for higher concentrations). In another example,bi-color LED 480 emits a green wavelength for low concentrations and ared wavelength for concentrations exceeding a threshold value. In analternative embodiment, the second LED is controlled by the controllerto flash during a testing period of a leak testing application of thesensor apparatus, to provide a steady signal when the presence of thetracer gas is detected by the sensor, and not emit light if the testingperiod concludes without the detection of the tracer gas.

[0114] Referring to FIGS. 19 and 20, an exemplary embodiment of sensorapparatus 450 is shown including a housing 496. Housing 496 isconfigured to enclose controller 452, sensor 454, power supply 456 (ifincluded), and indictor 458. Further housing 496 is configured toenclose a portion of member 460, such as CAN transceiver 492, CANcontroller 494, and RS-485 transceiver 490. However, as shown in FIG.19, sensing element or transducer 467 of thermal conductivity sensor 466is accessible from the exterior of housing 496 and is positionedgenerally proximate to the exterior of housing 496. Further, as shown inFIG. 20, indicator 458 is at least viewable from the exterior of housing496.

[0115] As shown in FIGS. 19 and 20, a first portion 497 of housing 496is configured to couple housing 496 to another component, such asfixture 133 shown in FIG. 3 in connection to a leak testing application.In the illustrated embodiment first portion 497 is threaded such thatfirst portion 497 may be threaded into a threaded aperture (not shown).A nut 498 is shown threaded onto first portion 497. Nut 498 assists incontrolling the degree of engagement between first portion 497 and thethreaded aperture (not shown). A second portion 499 of housing 496configured to be coupled by a tool. In the illustrated embodiment,second portion 499 is faceted such that second portion 499 may begripped by a wrench to aid in the engagement or disengagement of firstportion 497 with the threaded aperture.

[0116] Referring back to FIG. 17, I/O interface 460, in the illustratedembodiment, is configured to provide one of three outputs to externaldevices. First, I/O interface 460 is configured to provide an analogoutput through connection 482 which is coupled to controller 452 throughconnection 484. In one exemplary embodiment, controller 452 provides ananalog signal scaled between 0 to 2.5 volts which is representative ofthe sensing signal from sensor 454.

[0117] Second, I/O interface 460 is configured to provide a RS-485network compatible signal through connections 486 and 488. I/O interface460 includes a suitable transceiver 490 configured to comply with theRS-485 standard to communicate with other devices configured to complywith the RS-485 standard over a network. RS-485 transceiver 490 iscontrolled by controller 452 through various connections. RS-485transceiver 490, in the illustrated embodiment, is Model No. ADM485,available from Analog Devices.

[0118] Third, I/O interface is configured to provide a CAN networkcompatible signal through connections 486 and 488 or additionalconnections. I/O interface includes a suitable CAN transceiver 492configured to comply with the CAN standard to communicate with otherdevices configured to comply with the CAN studied over a CAN network anda suitable network controller, such as CAN controller 494, configured toconnect controller 452 and CAN transceiver 492. CAN transceiver 492 iscontrolled by CAN controller 494 and CAN controller 494 is controlled bycontroller 452 through various connections with controller 452. CANtransceiver 492, in the illustrated embodiment is Model No. MCP2551 andCAN controller 494 is Model No. MCP2510, both available from MicrochipTechnology, Inc. located at 2355 West Chandler Blvd., Chandler, Ariz.85224-6199.

[0119] The selection of which output type, analog, RS-485, or CAN, tosend an output signal over is under the control of controller 452. In apreferred embodiment, controller 452 of sensor apparatus 450 isprogrammable to have a plug and play type functionality such thatcontroller 452 is capable of recognizing what type of network includingthe absence of a network is connected to sensor apparatus 450. Theoperation of the plug and play functionality and additional functions ofcontroller 302 are discussed with reference to FIGS. 21-24 below.

[0120] Turning to FIG. 21, a flowchart of exemplary software 500configured to provide a plug and play type functionality to controller302 and to configure controller 302 for a leak testing application isshown. Software 500 includes a power on or reset routine 502corresponding to functions to be exercised during a reset of sensorapparatus 450 or to delay the operation of further tasks until it isdetermined that sensor 454 is warmed up and ready to detect the airsurrounding sensor apparatus 450. Further, configuration steps 504 and506 configure the sensor apparatus 450. Configuration step 504configures controller 452 including loading setup control parameters,such as network address and sensor constants. Configuration step 506configures CAN controller 494.

[0121] Once sensor apparatus 450 is configured, software 500 checks tosee if a network is currently connected to sensor apparatus 450, asrepresented by block 508. If a network is not detected, software 500enables analog output to be generated by controller 452 through a D/Aconverter, as represented by block 510. The analog output is thenavailable over connection 482 as explained above. Further, software 500enables a loop 511 wherein the analog data from sensor 454 is convertedto digital data by controller 452 and then reconverted to analog data bycontroller 452 such that the analog data is accessible throughconnection 482, as represented by block 512. In one example, the analogdata produced by controller 452 is different than the analog datareceived from sensor 454 due to scaling of the data.

[0122] Loop 511 includes the steps of reading the analog data fromsensor 454 through an A/D converter, as represented by block 514,process and scale the received data, as represented by block 516, andsend the resultant data if any to the D/A converter such that the datais accessible through connection 482, as represented by block 518. Inone example, controller 452, processes the data to determine if the datacorresponds to the detection of a threshold concentration of the tracergas and generates appropriate instruction to I/O member 460 andindicator 458. The threshold concentration or value in one example isprogrammed into sensor controller 452. In another example, the thresholdvalue is communicated to sensor controller 452 from a remote device.

[0123] As loop 511 is executing, software 500 is monitoring for possiblenetwork activity indicating that a network has been connected to I/Omember 460, as represented by block 520. If no network activity isdetected, loop 511 continues. However, if network activity is detectedthe D/A output (the analog output) is discontinued, as represented byblock 522 and the network activity is tested to determine if a validnetwork is connected, as represented by block 508. If the activity isnot a valid network, the D/A output is again enabled, block 512, andloop 511 is again commenced.

[0124] Assuming a valid network is detected, software 500 checks to seeif a test run flag has been set, as represented by block 524. The testrun flag is an indication from either controller 452 or a device acrossthe network such as PLC 118 or computer 116 that a leak test applicationhas been initiated. Typically, a leak test application is executed for aspecific time frame. As such, sensor apparatus 450 is configured toprovide sensing data, such as a sensing signal, during the time frame ofthe leak test application.

[0125] Assuming the run test flag has been set, software 500 checks tosee if an A/D result is ready, as represented by block 526. The A/Dresult corresponding to a digital signal representative of the output ofsensor 454. In one example, controller 452 is configured to take areading from sensor 454 at discrete time intervals, such as about every100 ms. A value corresponding to the reading, in one example, is storedin a memory accessible by controller 452. As such, software 500 checksto see if a current value has been stored in the memory. If a currentvalue is not stored, software 500 waits for a current value unless aninterrupt or other function needs to be performed, such as checkingonboard diagnostics, as represented by block 528. An example type ofonboard diagnostics is to check for sensor failures, as represented byblock 530. If a sensor failure is detected, software 500 generates andtransmits an error packet, as represented by block 532, over the networkto other devices, such as PLC 118 or computer 116.

[0126] If a current value is stored in the memory, software 500 clearsthe current result from memory, as represented by block 534 andgenerates and transmits a data packet including the current result frommemory, as represented by block 536. The data packet is transmitted overthe network to other devices, such as PLC 118 or computer 116.

[0127] Software 500 although discussed in a generally progressive manneris not bound to a progressive execution. In one embodiment, software 500checks at periodic time intervals for an interrupt routine, or a changein a parameter or flag, or the presence or absence of network activity.A first example interrupt routine 550 is shown in FIG. 22. Interruptroutine 550 corresponds to the reception of a network message across anetwork, such as a CAN network. The network message includes a commanddirected at sensor apparatus 450 and configured to either request orcommand sensor apparatus to perform a function. Software 500 isconfigured to interpret the command that was sent, as represented byblock 552.

[0128] Four exemplary command types are shown in FIG. 22. First, a testcommand type, as represented by block 554, corresponds to commandsdirected to the initiation or cessation of a testing time period oradditional commands related to a testing time period. A first examplecommand, as represented by block 562 corresponds to a test startcommand. Software 500 in response sets a test run flag to indicate thata test time period has begun, as represented by block 564. A secondexample command, as represented by block 566 corresponds to a test stopcommand. Software 500 in response clears a test run flag to indicatethat a test time period has ended, as represented by block 568.

[0129] Second, an update data command type, as represented by block 556,corresponds to commands requesting that the data from the sensorapparatus be updated or verified. A first example command to update andverify data is represented by block 570. Software 500 in responsegenerates and transmits a response with the requested data, asrepresented by block 572.

[0130] Third, a read data command type, as represented by block 558,corresponds to commands requesting that the data stored in the memory ofthe sensor apparatus be read and sent. A first example command to readdata from a memory is represented by block 574. Software 500 in responsegenerates and transmits a response with the retrieved data, asrepresented by block 576.

[0131] Fourth, an update sensor command type, as represented by block560, corresponds to commands either requesting the value of a currentsensor apparatus parameter or updating a sensor apparatus parameter. Afirst example command to provide a new parameter value to sensorapparatus 450 is represented by block 578. Software 500 in responsegenerates and transmits a response indicating that the parameter valuehas been changed, as represented by block 580.

[0132] A second example interrupt routine 582 is shown in FIG. 23.Interrupt routine 582 corresponds to a watchdog service routine. Thewatchdog service routine checks to see if a RESET command is received,as represented by block 584 and to generate a RESET of sensor apparatus450, as represented by block 586. In one example, the RESET command isreceived across the network. In another example, the RESET command isreceived due to an operator depressing a RESET button (not shown)located on the exterior of sensor apparatus 450 or otherwise initiatinga RESET command. In yet another example, the RESET command is generatedby the controller itself, signifying that it has become unstable or isin a locked state.

[0133] A third example interrupt routine 588 is shown in FIG. 24.Interrupt routine 588 corresponds to a A/D Result Ready routine. Asexplained in connection with FIG. 21, software 500 monitors to see if anA/D result is ready corresponding to a data value from the sensor 454.Interrupt routine 588 is one mechanism by which software 500 determinesthat a data value corresponding to sensor 454 is available. Theinterrupt routine 588 includes reading A/D values, as represented byblock 590, and to set a A/D result ready flag to let software 500 knowthat a new data value is ready, as represented by block 592.

[0134] In one embodiment of sensor apparatus 450, all or substantiallyall the electronics of sensor apparatus 450 including sensor controller452, I/O member 460 including the corresponding electronics for at leastone network type, and sensor 454 are all designed to be incorporatedinto a custom chip (not shown) to reduce the overall size of sensorapparatus 450. In one example the thermal conductivity sensor 466 iscoupled to a surface of the custom chip (not shown) containing all orsubstantially all the electronics. In another example, the thermalconductivity sensor is configured as a component of the custom chip (notshown), such that the sensing element or transducer of the thermalconductivity sensor is positioned on the exterior of the chip or isaccessible from the exterior of the chip. By making various connectionswith the leads of the custom chip a network such as a CAN network or anRS-485 network can be connected to the custom chip. The reduced size ofsensor apparatus 450 along with the superior sensing ability of sensorapparatus 450 makes sensor apparatus 450 ideal for incorporation into acomponent, such as an automobile, as a safety sensor. Sensor apparatus450 will share information with a controller (not shown) of thecomponent to relay information and data concerning the presence oramount of a gas.

[0135] In another embodiment sensor apparatus 450 is configured tooperate in a second mode of operation similar to sensor apparatus 300′of FIG. 15 and is designed to be incorporated into a custom chip (notshown) to reduce the overall size of sensor apparatus 450. As such,sensor apparatus 450 does not include an indicator, such as indicator458. In addition since sensor apparatus 450 will be connected to aremote controller through I/O member 460, the power needed at least bycontroller 452 and sensor 454 can be provided through I/O interface 460instead of through power supply 476. In one example the thermalconductivity sensor 466 is coupled to a surface of the custom chip (notshown) containing all or substantially all the electronics. In anotherexample, the thermal conductivity sensor is configured as a component ofthe custom chip (not shown), such that the sensing element or transducerof the thermal conductivity sensor is positioned on the exterior of thechip or is accessible from the exterior of the chip. By making variousconnections with the leads of the custom chip a network such as a CANnetwork or an RS-485 network can be connected to the custom chip. Asstated before, the reduced size of sensor apparatus 450 along with thesuperior sensing ability of sensor apparatus 450 makes sensor apparatus450 ideal for incorporation into a component, such as an automobile, asa safety sensor. Sensor apparatus 450 will share information with acontroller (not shown) of the component to relay information and dataconcerning the presence or amount of a gas.

[0136] Referring to FIGS. 25 and 26, an exemplary embodiment of sensorapparatus 450 is shown wherein all or substantially all of theelectronics of sensor apparatus 450 are incorporated into a custom chip.Sensor apparatus 450 includes a housing 596, which is configured toenclose the custom chip (not shown) and sensor 454. Further housing 596is configured to enclose a portion I/O interface 460, such as CANtransceiver 492, CAN controller 494 which may be incorporated into thecustom chip (not shown). However, as shown in FIG. 25, sensing elementor transducer 467 of thermal conductivity sensor 466 is accessible fromthe exterior of housing 596 and is positioned generally proximate to theexterior of housing 596. Further, as shown in FIG. 26, I/O interface 460is accessible from the exterior of housing 596.

[0137] As shown in FIGS. 25 and 26, a first portion 597 of housing 596is configured to couple housing 596 to another component. As shown inFIG. 27, sensor apparatus 450 is positioned in several locations on acomponent 700, such as an automobile. Sensor apparatus 450 a and 450 bare coupled to a fuel system 702 of automobile 700 and sensor apparatus450 c is coupled to an exhaust system 704 of automobile 700. Sensorapparatus 450 a, 450 b, and 450 c are connected through I/O interfaces460 a, 460 b, and 460 c to a component controller 706 of automobile 700.

[0138] Although the invention has been described in detail withreference to certain illustrated embodiments, variations andmodifications exist within the scope and spirit of the present inventionas defined in the following claims.

We claim:
 1. An apparatus for detecting the presence of at least oneleak in a first region of a part under test and for localizing thelocation of the at least one leak, wherein a first side of the firstregion contains a tracer gas and is at a higher pressure than a secondside of the first region such that the tracer gas will emanate throughthe at least one leak from the first side to the second side, theapparatus comprising: a plurality of sensors positioned proximate to thefirst region, each sensor being configured to detect the presence of atracer gas emanating from a leak and to provide a sensing signal; and acontroller connected to the plurality of sensors and configured toprovide a leak detection signal in response to at least a first sensorof the plurality of sensors detecting the presence of the tracer gas,the leak detection signal including leak detection informationrepresentative of the location of the leak in the first region based onthe sensing signals received from at least the first sensor and a secondsensor of the plurality of sensors.
 2. The apparatus of claim 1, furthercomprising an indicator configured to provide a visual indication of thelocation of the leak.
 3. The apparatus of claim 2, wherein the indicatorincludes a display configured to display a first representation of thepart under test and a sensor icon positioned on the firstrepresentation, the sensor icon corresponding to a location of a firstsensor which is proximate to the location of the leak.
 4. The apparatusof claim 3, wherein the sensor icon provides a visual indication of thelocation of the leak.
 5. The apparatus of claim 2, wherein the indicatorincludes a display configured to display a first representation of thepart under test and a leak graphic positioned on the firstrepresentation, the position of the leak graphic corresponding to alocation of a first sensor which is proximate to the location of theleak.
 6. The apparatus of claim 5, wherein the leak graphic is ananimated graphic configured to simulate the tracer gas emanating fromthe leak.
 7. The apparatus of claim 1, wherein the leak detection signalis provided in response to a determination that a threshold amount ofthe tracer gas has been detected by at least one sensor of the pluralityof sensors.
 8. The apparatus of claim 7, wherein the leak detectionsignal includes an indication of a first sensor, the first sensor beingchosen based on a determination that the at least one leak is positionedproximate the first sensor.
 9. The apparatus of claim 8, wherein thefirst sensor corresponds to the sensor that detected the highestconcentration of the tracer gas.
 10. The apparatus of claim 8, whereinthe first sensor corresponds to the sensor which first detected thepresence of the tracer gas.
 11. The apparatus of claim 1, wherein theleak detection signal includes an indication of the leak rate of the atleast one leak.
 12. The apparatus of claim 11, wherein the plurality ofsensors are coupled to a fixture, the fixture being configured tosubstantially enclose the first region and the leak rate of the at leastone leak being determined by finding the slope of the averageconcentration of tracer gas detected by the plurality of sensors overtime.
 13. A method of monitoring a part under test to determine whethera first region contains a leak, the method comprising the steps of:locating a plurality of sensors proximate to the first region, each ofthe plurality of sensors configured to detect the presence of a tracergas emanating from the leak and to provide a sensing signal; monitoringeach of the plurality of sensors to determine if the tracer gas is beingdetected by any of the plurality of sensors; and providing a leakdetection signal in response to at least a first sensor of the pluralityof sensors detecting the presence of the tracer gas, the leak detectionsignal including leak location information representative of thelocation of the leak in the first region based on the sensing signalsreceived from at least the first sensor and a second sensor of theplurality of sensors.
 14. The method of claim 13, further comprising thestep of providing a first indication of the location of the leak. 15.The method of claim 14, wherein the first indication includes displayingon a display a first representation of a part under test and a sensoricon positioned on the first representation, the sensor iconcorresponding to a location of a first sensor which is proximate to thelocation of the leak.
 16. The method of claim 14, wherein the firstindication includes displaying on a display a first representation of apart under test and a leak graphic positioned on the firstrepresentation, the position of the leak graphic corresponding to alocation of a first sensor which is proximate to the location of theleak.
 17. The method of claim 13, wherein the step of locating theplurality of sensors comprises the steps of coupling the plurality ofsensors to at least a first fixture and positioning the first fixtureadjacent the first region.
 18. The method of claim 17, wherein the firstfixture is configured to substantially enclose the first region suchthat tracer gas emanating from the leak is substantially retained by thefirst fixture.
 19. The method of claim 18, further comprising the stepof providing a leak rate signal in response to the at least first sensorof the plurality of sensors detecting the presence of the tracer gas,the leak rate signal including leak rate information representative ofthe leak rate of the leak.
 20. The method of claim 18, wherein the stepof providing the leak rate signal comprises the steps of: determiningaverage concentration of the plurality of sensors; monitoring the changein average concentration of the plurality of sensors over a first timeperiod; determining the rate of change of the average concentration overtime; and comparing the rate of change of average concentration to knownleak rates.
 21. The method of claim 13, wherein the leak detectionsignal includes information representative of the leak rate and themethod further comprising the step of providing a second indication of aleak rate in response to the at least first sensor of the plurality ofsensors detecting the presence of the tracer gas.
 22. A computerreadable media for use in a leak testing application to determine whichof a plurality of sensors is proximate to a leak in a part under test,the computer readable media comprising: a software portion configured toload a data file corresponding to the location of the plurality ofsensors, to monitor the plurality of sensors to determine if any of theplurality of sensors has detected the presence of a leak, to determinethe location of the leak if at least a first sensor of the plurality ofthe sensors detected the presence of the leak, and to provide a visualindication of the location of the leak if at least the first sensor ofthe plurality of the sensors detected the presence of the leak.
 23. Thecomputer readable media of claim 22, wherein the software portion isfurther configured to provide a first representation of the part undertest and a first sensor representation of the at least first sensorpositioned on at least the first representation of the part under test.24. The computer readable media of claim 23, wherein the visualrepresentation of the at least first sensor is a sensor icon.
 25. Thecomputer readable media of claim 23, wherein the first sensorrepresentation is the visual indication of the location of the leak. 26.The computer readable media of claim 22, wherein the software portion isfurther configured to determine the location of the leak by determiningwhich sensor of the plurality of sensors detected the maximumconcentration of a tracer gas emanating from the part under test. 27.The computer readable media of claim 22, wherein the software portion isfurther configured to determine the location of the leak by determiningwhich sensor of the plurality of sensors first detected the presence ofa tracer gas emanating from the part under test.
 28. The computerreadable media of claim 22, wherein the software portion is furtherconfigured to determine the leak rate of the leak in the part undertest.
 29. The computer readable media of claim 28, wherein the softwareportion is configured to determine the leak rate of the leak in the partunder test by determining an average concentration of a tracer gasdetected by the plurality of sensors; monitoring the change in theaverage concentration of the tracer gas detected by the plurality ofsensors over a first time period; determining a rate of change of theaverage concentration of the tracer gas detected by the plurality ofsensors over a second time period; and comparing the rate of change ofaverage concentration of the tracer gas detected by the plurality ofsensors to known leak rates.
 30. The computer readable media of claim28, wherein the software portion is further configured to provide a leakgraphic positioned on the first representation of the part under test ata location proximate to the location of the leak.